Identifying elderly women with osteoporosis by spinal dual X-ray absorptiometry, calcaneal quantitative ultrasound and spinal quantitative computed tomography: a comparative study.

The ability of spinal dual x-ray absorptiometry (DXA), calcaneal quantitative ultrasound (QUS) and spinal quantitative computed tomography (QCT) to identify women with osteoporosis within the GISELA study was evaluated in 43 women, aged 62-87 years. Osteoporosis was defined as a T-score below or equal to -2.5 using DXA (femoral neck). To determine the performance of each method, the sensitivity, specificity and area under the curve (by means of a receiver operating characteristic [ROC] analysis) were calculated. The median T-scores from the measurements differed significantly (p < 0.0001). DXA (spine) identified 75% of women with osteoporosis; QUS and QCT identified 100%. The specificity was 89% for DXA (spine), 66% for QUS and 29% for QCT. ROC analysis showed that all three methods are qualified to identify women with osteoporosis; however, the different sensitivities and specificities of the methods, as well as the thresholds used for diagnosing osteoporosis have to be considered.